Lexmark T640 - Printing order

We are a busy office, printing approx 300-400 documents per day.

The Lexmark T640 is running on a network (stand alone, not through a local pc)

When we run a large print job, the documents are printed out of order (we ran a Samsung network printer prior to the Lexmark - this always printed in order)

Is there a setting on the printer to stop this happening?

Many thanks

Phil Ware